Today, especially due to the delivery of multimedia services over Wi-Fi, more and more equipment is being connected to the in house WLAN (WLAN: Wireless Local Area Network). However, a lot of devices do not yet have the necessary hardware “on board” to be able to connect to the WLAN, but simply connect on Ethernet. Hence there is a booming demand for Wi-Fi-to-Ethernet boxes that allow easy connection of the Ethernet devices to the WLAN. One of the reasons that a lot of devices deliberately choose not to integrate WLAN hardware is because of the high pace with which the underlying 802.11 technology is evolving. While it took 802.11bg roughly ten years to get to a mature market, 802.11n rose to popularity in three years only to be followed-up by 802.11ac in 2013. Practically this means that devices embedding Wi-Fi technology have the chance to get obsolete or at least less popular quite fast. This puts a lot of pressure on the product cost, motivating stand-alone Wi-Fi-to-Ethernet boxes.
From a production cost point of view, a device manufacturer is interested in building the most versatile product in order to spend as little as possible on hardware tooling, i.e. production line, test software, etc., and as little as possible on logistic costs, e.g. caused by different product codes, different order numbers, software, required storage space, etc. Hence a single Wi-Fi-to-Ethernet device capable of being both AP and STA (AP: Access Point; STA: Station) is often realized, keeping production and logistic costs low. For ease of use, all devices receive AP credentials, which guaranties strong security. End users do not have to come up with clever passphrases and, through using WPS-PBC (WPS-PBC: Wi-Fi Protected Setup—2.Push Button Configuration), do not even need to know the WPA (WPA: Wi-Fi Protected Access) passphrase of the AP. This further removes the need for any user interface on the bridge devices, reducing the complexity and cost even further.
Not having to perform a lot of networking functions, Wi-Fi-to-Ethernet boxes are deployed as 802.1d compliant bridges, forwarding packets transparently between the devices connected to the AP and devices connected to the STA.
The main problem to overcome with such Wi-Fi-to-Ethernet boxes is the configuration of the network credentials. Ideally, end-users do not have to be troubled with the configuration of those devices and should be capable of using the devices right out of the box. This implies that the out-of-the-box (OOB) settings must allow deploying a WLAN, which is commonly realized via “pre-pairing” two or more devices in production. An alternative is the usage of WPS-PBC configuration, which becomes applicable once the end user starts to expand his current WLAN.
However, problems arise when users start to physically alter the network. For example, when a user moves to a new home and does not know which box was the AP and which one was the STA.
This is an issue as there is an impact on the usable bandwidth and this could lead to not being able to connect to the WLAN anymore.
This is illustrated in FIGS. 1 and 2 using a Wi-Fi LAN device as an example. In the example of FIG. 1 two STA devices STA1 and STA2 are connected to an AP, which in turn is connected to a central gateway or port of a broadband network. STA1 and STA2 have the credentials of the AP and hence are allowed on the WLAN. Because the two STA devices share the WLAN bandwidth using CSMA-CA (CSMA-CA: Carrier Sense Multiple Access with Collision Avoidance), each STA device roughly gets 50% of the available air-time, provided each is using the same PHY rate (PHY rate: Physical Layer rate).
When the end user decides to physically move the devices, the scenario can change as indicated in FIG. 2. As all the devices are generic, they all look the same. As a result the end user may unknowingly connect the devices in an incorrect way. Now the STA2 device is connected to the central gateway or port of the broadband network instead of the AP. This connection error cuts the available bandwidth to 33% per STA device. The reason of this bandwidth drop is the IEEE 802.11 infrastructure mode, which does not allow STA devices to exchange data directly with each other. Instead, all packets must go through the AP.
Thanks to the pairing or pre-pairing the Wi-Fi link will still work, but there is a substantial bandwidth loss. Note that the example given still considers equal PHY rate between the clients and the AP. If this starts to change due to external influences, e.g. fading, shadowing, interference, etc., the impact becomes a lot worse.
From the scenario in FIG. 2 it is apparent that a functional role change is required. Functional role change here means that an AP becomes an STA or an STA becomes an AP. This is needed in order to restore the air-time ratio and hence the total throughput towards a client.
A role change is by preference dynamic, e.g. using a discovery mechanism such as LLDP (LLDP: Link Layer Discovery Protocol), SSDP (SSDP: Simple Service Discovery Protocol) or even DHCP (DHCP: Dynamic Host Configuration Protocol), so that an end user is not troubled with a full, manual reconfiguration. A solution for determining a role change of network devices is described, for example, in U.S. Pat. No. 7,380,025.
FIG. 3 illustrates what happens when a role change is performed. STA2 becomes a new access point AP(2) using its own set of credentials, i.e. BSSID (BSSID: Basic Service Set Identification) and WPA passphrase. The other devices can reconnect to the network, as they have been pre-paired. However, if the devices were not pre-paired, e.g. because the end user bought two separate devices, or a third device was added, or a device was replaced, the scenario of the role swap would lead to a disaster, as the other devices would not be able to reconnect to the network.